If hydration is the problem, then you should be able to resolve that problem over time by making adjustments to the amounts of flour and water. However, without a scale, you will not know what hydration you are actually getting and you may not get consistent and reproducible dough balls as a result. Over time you may get the desired finished dough consistency, or some semblance of it, but it will take making a lot of dough balls.
It seems to me that your dough preparation method is somewhat unorthodox. I'd like to suggest the following method for preparing and hand kneading your dough:
1. If you have a sieve or hand crank sifter, sift the formula flour into a first bowl and add and stir in the IDY. (See Note 2 below if using ADY instead of IDY.) The IDY can also be sifted along with the flour if the openings of the sieve or sifter are large enough. Sifting the flour will improve the hydration of the flour by incorporating more water into the dough. Unlike ADY, it is not necessary to rehydrate the IDY in warm water.
2. Put all of the formula water into a second bowl, add the salt, and stir until dissolved, about 30 seconds. When using IDY, it is not necessary to warm up the water (e.g., to around 105 degrees F). Using warm water will only increase the finished dough temperature and accelerate the fermentation of the dough and shorten its window of usability. The water can be cool or even cold right out of the refrigerator. Ideally, for a home refrigerator application, you want the finished dough temperature to be between 75-80 degrees F. Using cool/cold water should allow you to achieve a finished dough temperature in that range. A thermometer (e.g., an analog or digital instant read thermometer) will be required to measure the finished dough temperature.
3. Add the oil to the bowl with the water/salt mixture. Alternatively, the oil can be added after step 4 below and incorporated into the dough. (Some people feel that the oil interferes with the hydration of the flour if added to the water. On the other hand, adding the oil to the water disperses it more uniformly throughout the dough as it is kneaded into the dough.)
4. Gradually add the flour/yeast mixture to the water/salt mixture a few tablespoons at a time and, using a sturdy spoon, combine the ingredients until you can no longer stir more of the flour/yeast mixture into the dough mass with ease. If desired, a wire whisk can be used at the beginning to improve the hydration of the flour even more, and switch to the spoon when the whisk bogs down. If the oil was not added in step 3 above, add to the oil to the dough in the mixing bowl and knead into the dough.
5. Using a spatula or a flexible plastic bench knife, scrape the rough dough mass out of the mixing bowl onto a work surface that has been lightly dusted with a bit of the remaining flour/yeast mixture.
6. Sprinkle the remaining flour/yeast mixture a little bit at a time onto the dough mass and knead into the dough mass after each addition. To facilitate this process, use wet hands or hands dusted with a bit of the flour. It is also possible to use a bench knife, or even two of them for a large dough batch, to turn the dough mass as the remaining flour is added to the dough. For some guidance on how to use a bench knife to help knead the dough, see this video: http://www.monkeysee.com/play/997-pizza-how-to-make-dough-by-hand-part-two
. If the dough is hard to knead for any reason, let the dough rest from time to time during the kneading process. This will allow the flour to better hydrate and will allow the gluten structure to relax and become less elastic, making it easier to knead the dough.
7. Continue kneading until the dough is smooth and malleable yet a bit tacky. Resist the temptation to add more flour. As the hand kneading continues, the wetness of the dough should gradually diminish and disappear. If the dough really sticks to your fingers and to the work surface (the dough will usually pull away in strands as it is pulled away from the work surface), add additional flour, a quarter teaspoon or half teaspoon at a time, and knead into the dough with each such addition. If the dough is too dry, add more water, about a half teaspoon at a time, and knead to incorporate. If more flour and/or water are used in this manner, note the total amounts of each added. This might help you modify your dough formulation for future dough batches, especially if you use a scale to weigh the flour and water.
8. Another dough kneading method I often use, usually for fairly high-hydration doughs coming out of my stand mixer, but which can also be used as part of a hand kneading regimen, is the one shown in Images 4a-4c at http://www.woodstone-corp.com/cooking_naples_style_dough.htm
Note 1: It is also possible to add the salt to the flour rather than to the water in the mixing bowl. The same also applies to sugar (if called for in the dough formulation). However, I prefer to add both salt and sugar to the water, which helps them dissolve faster and better. If honey is used in lieu of sugar, it can be added to the water in the mixing bowl or to the dough in the bowl as it is being mixed and kneaded. The honey can be warmed up slightly to make it flow better but that step is optional.
Note 2: If ADY is used instead of IDY, it should be rehydrated in a small amount of the formula water at about 105 degrees F for about 10-15 minutes. It can then be added to the rest of the formula water or to the rest of the ingredients in the mixing bowl. If fresh (cake) yeast is used, it can either be rehydrated in tepid water (a portion of the formula water) at around 80-90 degrees F, or simply be crumbled into the mixing bowl.
Note 3: If weights of ingredients are used and one of the dough calculating tools is used, it is recommended that a bowl residue compensation of 1.5-2% be used in the tool to compensate for minor dough losses during preparation of the dough.
If you have an electric hand mixer, another kneading regimen that combines use of the electric hand mixer and hand kneading is described at Reply 30 at http://www.pizzamaking.com/forum/index.php/topic,3985.msg36489.html#msg36489
. You will note many of the steps suggested above are also incorporated in the procedures described in that post.
EDIT (6/14/16): For a Wayback Machine version of the above inoperative Woodstone link, see http://web.archive.org/web/20090215125027/http://www.woodstone-corp.com/cooking_naples_style_dough.htm